1. Field of the Invention
The present invention generally relates to devices for interconnecting optical fibers, and more particularly to a combination dust cap and actuation tool for an adhesiveless fiber optic connector.
2. Description of the Prior Art
Optical fibers have now surpassed copper wire as the preferred medium for telecommunications. As with copper wire, it often becomes necessary to interconnect optical fibers, for example, during installation or repair. The present invention is directed to a tool used to secure an optical fiber to a fiber optic connector, in order to complete and install such interconnections. In this regard, a fiber optic "connector" often refers to a device which allows repeatable engagement and disengagement of the cable, while a "splice" typically refers to a device which is used for the permanent attachment of two cable ends. These terms should not, however, be construed in a limiting sense as used herein since the present invention is applicable to the installation of all classes of fiber optic interconnection devices.
The prior art includes ferrule-type fiber optic connectors having a cylindrical member (the ferrule) usually made of a ceramic material, zirconia, or alumina, with a central bore for receiving the fiber. The ferrule is held by a collar which in turn may be surrounded by one of many different coupling shells. For example, a coupling shell having a bayonet-style latching mechanism is commonly referred to as an "ST" connector. An alternative shell having ramped surfaces which latch onto lever arms of a receptacle is known as an "SC" connector. Yet another shell having a simple threaded nut is known as an "FC" connector. There are many conventional techniques for securing an optical fiber in ferrule connectors. One of the most common is the use of a crimp tube which clamps the fiber optic cable reinforcing members (i.e., KEVLAR strands) to a backbone attached to the ferrule collar. See, e.g., U.S. Pat. No. 5,140,662. This technique requires the use of a plier-like crimping tool to compress the crimp tube about the backbone.
In another technique, illustrated in U.S. Pat. Nos. 5,088,804 and 5,102,211, an adhesiveless optical fiber termination is assembled by driving two telescoping workpieces together, compressing an elastomeric system seated within one of the workpieces to secure the optical fiber therein. This technique uses a different, rather complicated, tool having two primary elements which hold the workpieces and move toward one another for actuation. See also U.S. Pat. Nos. 5,080,460 and 5,131,063.
In U.S. Pat. No. 5,040,867, the fiber itself is secured in a clamping member within the ferrule collar, and the cable reinforcing strands are additionally secured by a crimping sleeve onto a backbone. In that design, a locking member slides over the ferrule collar and clamping member to secure the fiber. The locking member is actuated by another hand-held tool which moves the locking member along the axial direction of the fiber into the rear end of the connector. A separate dust cap is used to secure the forward end of the connector in the tool without damaging the ferrule.
One problem not addressed by these techniques is the proper positioning of the terminal end of the fiber, for example, to coincide with the end face of the ferrule. The foregoing techniques not only fail to take this problem into consideration, but they further make proper positioning difficult since the tools used to activate these connectors are designed to apply an axial force, i.e., parallel with the fiber axis, which tends to cause the fiber itself to move relative to the connector during the clamping process. Thus, precise registration of the fiber relative to the ferrule is impossible. Insertion of the connector into the assembly tool also adds a level of difficulty to the installation process. It would, therefore, be desirable to devise a tool which activates the clamping member of a fiber optic connector without disturbing the position of the fiber. It would further be advantageous to devise such a tool which precisely controls the position of the terminal end of the fiber with respect to the ferrule. It would also be desirable to incorporate such a tool into a dust cap for the connector to simplify installation of the fiber.